Radio signal transmitting antenna, radio signal receiving antenna, radio signal transmission/reception system, radio signal transmitting method, and radio signal receiving method

Abstract

The present invention is a radio signal transmitting antenna (10) including a first wave source (11) including a plurality of antenna elements (A1 to AN) configured to form a first helical beam (H) for OAM (Orbital Angular Momentum) from the plurality of antenna elements (A1 to AN) and output the first helical beam (H) and a second wave source (15) configured to receive the first helical beam (H) and form a second helical beam (L) output in a constant direction and transmits the second helical beam (L). The radio signal transmitting antenna (10) can transmit a helical beam (L) for OAM with a simplified and smaller device configuration.

What is claimed is: 
     
       1. A radio signal transmitting antenna comprising:
 a first wave source including a plurality of antenna elements configured to form a first helical beam for OAM (Orbital Angular Momentum) from the plurality of antenna elements and output the first helical beam; and 
 a second wave source configured to receive the first helical beam and form a second helical beam including a second electromagnetic field distribution, the second electromagnetic field distribution being an expanded first electromagnetic field distribution included in the first helical beam, 
 wherein the first wave source comprises:
 the N (integer N≥2) antenna elements arranged at equal intervals on a concentric circumference; and 
 a signal distribution circuit for generating, from an input first signal, N second signals having a phase difference from one another and outputting the N second signals having the phase difference from one another to the N antenna elements so that the first helical beam whose equiphase surface inclines in a helical manner is output from the N antenna elements, and 
 
 wherein when M (integer M≤N) different first signals are input, the signal distribution circuit distributes the second signals to the respective N antenna elements so that M different helical beams are output from the N antenna elements. 
 
     
     
       2. The radio signal transmitting antenna according to  claim 1 , wherein the second wave source comprises a first reflecting unit including a parabolic mirror part that reflects the first helical beam and forms the second helical beam. 
     
     
       3. The radio signal transmitting antenna according to  claim 2 , wherein the second wave source further comprises a second reflecting unit including a sub-reflecting mirror part that makes the first helical beam output from the first wave source be indirectly reflected on the first reflecting unit. 
     
     
       4. The radio signal transmitting antenna according to  claim 1 , wherein the second wave source comprises a third another reflecting unit including a lens surface part that refracts the first helical beam to form the second helical beam. 
     
     
       5. The radio signal transmitting antenna according to  claim 2 , wherein the signal distribution circuit distributes a signal so that the second signals including a predetermined phase difference that increases in a stepwise manner in a direction of the circumference are input to the adjacent antenna elements. 
     
     
       6. The radio signal transmitting antenna according to  claim 2 , further comprising another signal distribution circuit for receiving M different other first signals orthogonal to the first signals and outputting N other second signals orthogonal to the second signals in such a way that an orthogonal polarization of the first helical beam is formed from the N antenna elements. 
     
     
       7. The radio signal transmitting antenna according to  claim 1 , wherein the first wave source further comprises an antenna element that outputs a signal in a non-OAM mode.